Electronic devices often include connectors to provide ports where power and data signals can be shared with other devices. These connectors are often designed to be compliant with a standard, such that the electronic devices can communicate with each other in a reliable manner. The various Universal Serial Bus (USB), Peripheral Component Interconnect Express (PCIe), and DisplayPort (DP) standards are but a few examples.
Often, devices communicate over cables. These cables may have a plug or insert on each end, which plug into receptacles in the devices. But the data rates of these standards are increasing tremendously, and new types of cables are needed in order for devices to communicate at these higher data rates.
To meet these increased data rates, active circuits may be included in the cable. But these active circuits need to be powered. It is typically undesirable to provide power to these cables using a source other than one of the connected devices. That is, it may be undesirable to power a first cable using a second cable.
For this reason, power may be provided to active circuits in a cable by the devices being connected by the cable. But these devices may have unequal power delivery capabilities. For example, a first device may be powered by a wall outlet, while a second device may derive its power from the first device. Also, various devices may provide various voltage levels.
Thus, what is needed are circuits, methods, and apparatus that power active circuits in a cable in an intelligent and configurable manner. It may also be desirable to reduce power by providing various states such as sleep and other lower power states.